The present invention relates generally to a method of eradicating pests and, in particular, a method using heat to eradicate pests from a variety of products.
Wood products such as wood packing, pallets, dunnage, crating, blocks, cases, load boards, pallet collars, skids, plants and bulk food items are common carriers of non-resident pests (including termites, beetles, and other insects). Non-resident pests can devastate the forest ecosystems or timber production areas of both domestic and foreign countries.
All forests are particularly vulnerable to non-residential and exportation pests such as fungi, nematodes, or insects introduced through importation and exportation of logs, lumber, or non-manufactured wood articles. Because wood products produced in temperate areas outside of North America are afflicted with a wide variety of pests and diseases that are non-indigenous to this continent, they can be spread rapidly when introduced here. The primary reason is that natural predators of the pests in their indigenous regions are not present in North America. Conversely, wood products produced domestically can harbor pests and diseases which would be non-indigenous to other countries. Accordingly, special care is required to ensure that imported and exported wood and wood products are pest-free.
The introduction of non-indigenous pests and diseases could be detrimental to U.S. Forest Production, recreation, and urban forest resources. These pests bore into the roots, limbs, or trunk of a tree. The pests can interfere with a tree""s reproductive capabilities, can cause defoliation, wood damage, and/or create a shift in or cause changes in habitat and food supply. In addition, establishment of non-indigenous organisms has clearly been shown to reduce biodiversity.
There are several historical examples in which the importation of non-indigenous timber pest species has led to widespread blights within the United States and worldwide. Notable cases last century have included: Chestnut blight (Cryphonectria parasitica, 1904-1955), Dutch Elm disease (caused by the fungus Ophiostoma ulma, mid-1920""s), White Pine blister rust (fungus Cronartuum ribicola, early 1900""s), Port Oxford Cedar root rot (fungus Phytophthora lateralis, 1923), and the recent Gypsy moth (Lymantria dispar, 1970""s) outbreaks. Each of these outbreaks caused ecological damage such as shifts in species composition, changes in habitat, as well as tree defoliation, stress and death.
While the pesticide Methyl Bromide is currently being used to fumigate timber and wood products, it may not be the most effective treatment for controlling quarantined pests (e.g., bark beetles and borers, termites, and fungus) on imported or exported logs and lumber. Further, it is believed that Methyl Bromide does NOT penetrate effectively into wood that has a high moisture content. It is difficult to achieve useful insecticidal doses much beyond a depth of 100 millimeters in green materials using conventional tent fumigation techniques. Likewise, according to the USDA, xe2x80x9cthere is little scientifically derived efficacy data available to determine the most effective ways to employ Methyl Bromide fumigation to destroy plant pests associated with imported wood products.xe2x80x9d Additionally, recent test shipments of wood products imported into the U.S. that were fumigated with Methyl Bromide have been found to be infested with fungal pests upon arrival. Methyl Bromide, therefore, when used to treat logs and lumber, does NOT completely eradicate the risk of quarantined pests entering a new territory. Also the process and use of Methyl Bromide is being considered for a possible ban due to the detrimental environmental effects that this chemical has in people and the atmosphere and the lack of effectiveness it has had on this product range.
The subject invention relates to eradication of pests by the use of heat. While it is applicable to a wide range of pests including insect life, its most important application at the present time is the eradication of pests from products such as non-manufactured wood packing (e.g., pallets, dunnage, crating, packing blocks, cases, load boards, skids, etc.), paper products, appliances that hold and dispense foods or drinks (e.g. vending machines, water coolers, coffee machines), and machinery equipment, and commodities.
All pests, including insect life, have a temperature range within which it can survive and thrive. Temperatures appreciably above and below this range are lethal, and temperatures that are close to this range but still outside of the range will be lethal if maintained for a sufficiently long period of time. The causes of death vary from pest to pest. The precise mechanism by which the pest perishes is of no particular interest to the invention, but the fact that the pests perishes is the objective, and that it is killed without harm to the structure, environment or to people who utilize the structure.
The use of elevated temperatures to kill pests avoids the risks and inconveniences of using toxic gasses in fumigation techniques. There is no need to use anything but atmospheric air or other friendly gases, so that clean up after the process is unnecessary. The equipment is conventional and is operable by persons of few skills. Preparation for use in an occupied structure involves no more than removal of temperature sensitive material such as candles, and sometimes the placing of insulation matts.
This invention is a novel, effective, economical and safe means for exterminating pests and is accomplished by heating a region infested by pests to a suitably elevated temperature for a time sufficient to kill the pest but without harming the surrounding structure (e.g., a wood pallet) or the contents (e.g., bulk food). According to a preferred embodiment, a region to be treated is subjected to hot air for a period of time sufficient to raise the host material (the xe2x80x9cregionxe2x80x9d) temperature to the desired level, and to maintain it at that temperature for a suitable period of time. The xe2x80x9cregionxe2x80x9d to be treated may of course be only indirectly approached by the air itself. For example, the inside of an infested post will not directly be contacted by the air, but will be heated by heat conducted from the surface of the post, which is exposed to the convected air. The heated air will then be contained in a volume such as a room or other enclosed space.
A unique method in which products or materials, including but not limited to wood packing, pallets, dunnage, crating, blocks, cases, load boards, pallet collars, skids, machinery, or commodities, are placed in, or surrounded by, a controllable environment, which kills pests, molds, and fungus by heating them and their immediate environment in accordance with a specific time-temperature schedule that achieves a minimum core temperature of 56 degrees Celsius (133 degrees Fahrenheit) for thirty minutes or longer as required.
Heat treatment can be a very effective method for the eradication of pests without the drawbacks of fumigation e.g., highly toxic chemicals, airtight fumigation containment, certified pest controller(s), and lengthy treatment/clearing times. Numerous studies have documented that temperatures at or above 49 degrees Celsius (120 degrees Fahrenheit) for thirty minutes are lethal to most pests.
The above and other features of this invention will be fully understood from the following detailed description and the accompanying drawings.